using System;

​

namespace Abstract_Learn

{

    abstract class A

    {

        public void AddString(string arg1, string arg2)

        {

            Console.WriteLine( arg1 + arg2);

        }

        public virtual void display()

        {

            Console.WriteLine("Display -- A");

        }

        public virtual void displayA()

        {

            Console.WriteLine("Display -- A");

        }

        public virtual void show()

        {

            Console.WriteLine("Show -- A");

        }

        public abstract int x { get; set; }

        //abstract public static void Add(); //A static member 'Abstract_Learn.A.Add()' cannot be marked as override, virtual, or abstract

        abstract public void Add();

        abstract public void substract();

        abstract public void Multiply();

    }

    abstract class B : A

    {

        public new void display()

        {

            Console.WriteLine("Display -- B");

        }

        public new void show()

        {

            Console.WriteLine("Show -- B");

        }

        public void show(int a)

        {

            Console.WriteLine("Show -- B");

        }

        abstract public void Divide();

    }

    class normalClass : A

    {

        //What evere the abstract members or abstract fields in the abstract class, those are all needs to implement in the derived normal class

        public override int x { get; set; }

        public override void Add()

        {

            Console.WriteLine("Add-normalClass");

        }

        public override void substract()

        {

            Console.WriteLine("Substract-normalClass");

        }

        public override void Multiply()

        {

            Console.WriteLine("Multiply-normalClass");

        }

    }

    sealed class C : B

    {

        //What evere the abstract members or abstract fields in the abstract class, those are all needs to implement in the derived class

        public override int x { get; set; }

        public override void Add()

        {

            Console.WriteLine("Add-C");

        }

        public override void substract()

        {

            Console.WriteLine("Substract-C");

        }

        public override void Divide()

        {

            Console.WriteLine("Divide-C");

        }

        public override void Multiply()

        {

            Console.WriteLine("Multiply-C");

        }

    }

    public class program

    {

        public static void Main(String[] args)

        {

            C obj = new C();

            obj.Add();

            obj.Multiply();

            obj.Divide();

            Console.WriteLine("---------------------");

            obj.display();

            obj.displayA();

            obj.show();

            obj.AddString("A", "B");

            Console.WriteLine("---------------------");

            normalClass normal = new normalClass();

            normal.Add();

            Console.WriteLine("---------------------");

            //B objB = new B(); //Cannot create an instance of the abstract class or interface

        }

    }

}